Investigators from the School of Medicine at The University of Texas Health Science Center at San Antonio have determined the first high-resolution structure of an enzyme that, if partially inhibited, could represent a new ...

Pain from inflammation sidelines thousands of Americans each year. Many face a tough choice: deal with the pain, take a potentially addictive opioid or use a nonsteroidal anti-inflammatory drug that may increase risk for ...

Many proteins undergo an assembly line-style process of glycosylation as they travel from a cellular structure called the endoplasmic reticulum (ER) to the Golgi apparatus and on through its various compartments, after which ...

Enzyme supplements available without a prescription are becoming increasingly popular, but should everyone add them to their shopping list? Brent Bauer, M.D., director of the Mayo Clinic Complementary and Integrative Medicine ...

Researchers at Yale School of Medicine have pinpointed a mechanism in part of the brain that is key to sensing glucose levels in the blood, linking it to both type 1 and type 2 diabetes. The findings are published in the ...

(Medical Xpress)—Yale School of Medicine and Yale Cancer Center researchers have uncovered a genetic vulnerability of cancer cells that express telomerase—an enzyme that drives their unchecked growth—and showed that ...

Enzyme

Enzymes are biomolecules that catalyze (i.e., increase the rates of) chemical reactions. Nearly all known enzymes are proteins. However, certain RNA molecules can be effective biocatalysts too. These RNA molecules have come to be known as ribozymes. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.

Like all catalysts, enzymes work by lowering the activation energy (Ea or ΔG‡) for a reaction, thus dramatically increasing the rate of the reaction. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts by being much more specific. Enzymes are known to catalyze about 4,000 biochemical reactions. A few RNA molecules called ribozymes catalyze reactions, with an important example being some parts of the ribosome. Synthetic molecules called artificial enzymes also display enzyme-like catalysis.

Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase activity. Many drugs and poisons are enzyme inhibitors. Activity is also affected by temperature, chemical environment (e.g., pH), and the concentration of substrate. Some enzymes are used commercially, for example, in the synthesis of antibiotics. In addition, some household products use enzymes to speed up biochemical reactions (e.g., enzymes in biological washing powders break down protein or fat stains on clothes; enzymes in meat tenderizers break down proteins, making the meat easier to chew).